First of all, if you are asking the question of "how to save my marriage", first thing - I want to congratulate you for that.
The reason behind is simple - not many people fight for their marriages nowadays.
Because they don't have the qualities that marriage demands (commitment, loyalty, responsibility, selflessness), they simply choose to walk out at the first sign of trouble, instead of staying and fighting on.
I am like you - I have been in this situation, I have fought for my marriage, and I have saved my marriage.
Although - it wasn't easy.
When I first learned that my husband no longer wanted to stay married to me; I was desperate to do something to save my marriage and I begged to him: "Please George - do not end our marriage! I love you so much, I understand all my mistakes! They won't happen again - please George!"...
Of course, that didn't work.
That couldn't work.
My husband was already fed up to the bone with me and the marriage.
And by begging I only made him more fed up with me.
That not only didn't help, but made the whole situation worse.
But as I have said, I have saved my marriage in the end - but how? The key is to go against the flow.
At the moment, your mind is being stirred by your intense emotions because of the situation.
You are desperate to "do something" and you don't know what to do.
You are vulnerable to your emotions, and when they replace your rationality, they make you do the wrong things.
So, go against the flow (your emotions) and don't give in to what they say! The best thing in such situations is to ask for some outside advice, because things are much easier when you have a plan of action to stick to.